Multiple Neutrals

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mcna6992`

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Does the NEC permit 2 separate neutrals from 2 separate power supplies to be run inside of the same multi-conductor cable inside the same raceway?
 
Yes, but only if the ungrounded (phase) conductors and the equipment grounding conductor (if used) are also in the same cable. See 300.3(B).

Welcome to the forum.
 
mcna6992` said:
Does the NEC permit 2 separate neutrals from 2 separate power supplies to be run inside of the same multi-conductor cable inside the same raceway?

I for one would like to here more details on the install.

And welcome to the Forum.
 
I'd say different systems in the same raceway is not a good practice even if allowed. I've seen it done in old exit signs to comply with a fire code " ther must be two sources" Today we use battery back-up as the second source or the circuit is fed though a transfer switch. ther is a High potential that the nuetrals get mixed up.
 
There may be some issues with 200.6(D) about differentiating between the grounded conductors of the different systems. If #6 or smaller, it may be hard to find cable with proper conductor colors. 200.6(E) would have to be examined. In general, one of the conductors would need to be white, the other would need to be gray. The three-white stripe thing could be used for one of the conductors.... all of these would need to be actual insulation colors, not tape or marking. There are some exceptions.
 
There are striped conductors available for the purpose. e.g. 3 different 208/120wye systems - black-black stripe over white stripe, red-black stripe, blue-black stripe, white black stripe - same with red stripes, blue stripes - hot pink stripes if you like - so long as they are identified, and posted at the panels. See 210.4D (I think...)

And likewise, that would conform to 200.6D as you would have a 'black' system, a 'red' system, and a 'blue' system - each with identified neutrals, and hots to eliminate or reduce the chance of interconnecting them to accidentally produce another voltage all together. Then you could put circuits from the panels of all 3 panels, and all 3 transformers into the same gutter if you like - even add in some 480/277 systems too with other colored strips. (So long as none involve green) All easy to identify....

For that matter if you an not find striped wire - tape, zip-ties, clip-on wire markers, tags out of a book - "or other approved means"
 
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